Create a Simple Transaction Indexer on Juneo Supernet Using Squid SDK

In this tutorial, we will create a simple transaction indexer on the Juneo Supernet using the Squid SDK.

Before we begin, some of you might be wondering: What is Juneo Supernet, and what is Squid SDK?

Juneo Supernet is a blockchain ecosystem built upon the Snowman++ consensus protocol, a highly scalable and efficient version of the Avalanche consensus. It provides a permissionless platform for deploying decentralized applications (dApps) and custom blockchains.
Squid SDK is a developer toolkit for building data indexers on blockchain networks. It streamlines the process of extracting, processing, and querying on-chain data for applications like analytics dashboards, DeFi platforms, and dApps.

Let's dive in!

Prerequisites

Docker (for running PostgreSQL)
Node.js 20

Steps to Build the Indexer

1. Initialize the Project

Create a new folder and initialize a new project:

npm init

2. Install Required Packages

Run the following commands to install the necessary dependencies:

npm i dotenv typeorm @subsquid/evm-processor @subsquid/typeorm-store @subsquid/typeorm-migration @subsquid/graphql-server @subsquid/evm-abi
npm i typescript @subsquid/typeorm-codegen @subsquid/evm-typegen --save-dev

3. Add a Minimal tsconfig.json

Create a tsconfig.json file:

{
  "compilerOptions": {
    "rootDir": "src",
    "outDir": "lib",
    "module": "commonjs",
    "target": "es2020",
    "esModuleInterop": true,
    "skipLibCheck": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true
  }
}

4. Create a Simple GraphQL Schema

Create a schema.graphql file with the following content:

type Transaction @entity {
  id: ID!
  from: String! @index
  to: String! @index
  value: BigInt!
}

5. Generate TypeORM Model Entity

Run the following command to generate TypeORM models based on your schema:

npx squid-typeorm-codegen

6. Set Up the Database

Create a .env file:

DB_NAME=squid
DB_PORT=23798

Create a docker-compose.yaml file:

version: "3"
services:
  db:
    image: postgres:15
    environment:
      POSTGRES_DB: "${DB_NAME}"
      POSTGRES_PASSWORD: postgres
    ports:
      - "${DB_PORT}:5432"

Run the database container:

docker compose up -d

7. Generate and Apply Migrations

Compile the TypeORM classes:

npx tsc

Generate the migration file:

npx squid-typeorm-migration generate

Apply the migration:

npx squid-typeorm-migration apply

8. Create the Main Script

Create src/main.ts and add the following code:

import { EvmBatchProcessor } from '@subsquid/evm-processor';
import { TypeormDatabase } from '@subsquid/typeorm-store';
import { Transaction } from './model';

const ADDRESS = 'TARGET_ADDRESS EG 0x912312321hjahd123'.toLowerCase();

const processor = new EvmBatchProcessor()
    .setRpcEndpoint('https://rpc.socotra-testnet.network/ext/bc/JUNE/rpc')
    .setBlockRange({
        from: 9_083_000
    })
    .setFinalityConfirmation(75)
    .addTransaction({
        from: [ADDRESS],
        traces: true,
    })
    .addTransaction({
        to: [ADDRESS],
    })
    .setFields({
        transaction: {
            from: true,
            to: true,
            value: true,
            hash: true,
        }
    });

processor.run(new TypeormDatabase(), async (ctx) => {
    const txs: Transaction[] = [];
    for (let c of ctx.blocks) {
        for (let txn of c.transactions) {
            const tx = txn as any;
            if (tx.to === ADDRESS || tx.from === ADDRESS) {
                txs.push(new Transaction({
                    id: tx.hash,
                    from: tx.from,
                    to: tx.to,
                    value: tx.value,
                    hash: tx.hash,
                }));
            }
        }
    }

    await ctx.store.insert(txs);
});